The present invention relates to a method and an apparatus for controlling a tray changer incorporated in an NC (i.e., numerically controlled) machine tool or other robot control system. The tray changer of this invention conveys or carries trays each mounting a plurality of workpieces (i.e., materials or components to be machined or processed) thereon one by one into or out of the NC machine tool or the like.
The tray changer is connected or interfaced with an NC machine tool or the like to successively and efficiently supply each tray to the NC machine tool or the like. The tray mounts a plurality of workpieces arrayed thereon. The control of the tray changer is combined with the control of the robot. According to the operation of the tray changer, the workpieces to be machined or processed are carried in or out together with a tray mounting them. A robot, located between the tray and the NC machine tool, receives and delivers each workpiece from the tray to the NC machine tool and also returns a machined or processed workpiece (i.e., product) from the NC machine tool to the same or another tray. The robot, when manufactured, may be associated with a tray changer as an assembled or united facility. In some other cases, the user may join the robot to the tray changer at a later timing for the reasons of the user. The robot successively or selectively receives a workpiece carried on a tray after the tray changer positions a plurality of stacked trays at a predetermined position with respect to the robot. Then, the robot delivers and attaches a selected workpiece to the NC machine tool. Then, the robot detaches a machined or processed workpiece (i.e., product) from the NC machine tool and carries it to a designated tray placed separately from the stacked carry-in trays used for carrying this workpiece in. The delivery of the workpiece between the NC machine tool and the robot is usually direct or may be indirect in some cases.
In general, a plurality of empty trays each having the same size and configuration are stacked adjacently to the robot. When one tray (i.e., uppermost tray) is filled with the machined or processed workpieces (i.e., products), the filled tray is moved out to leave the next empty tray. The tray changer has a fundamental operation suiting for the above-described carrying in-and-out operation. The fundamental operation of the tray changer necessarily varies depending on the type or kind of workpieces to be machined or processed. The program used in controlling the tray changer needs to be modified accordingly.
If the robot is manufactured as a specialized device dedicated to the tray changer, it will be possible and easy to use the common program languages for the control in both of the robot and the tray changer.
On the contrary, when the robot is integrated or combined with the tray changer at a later timing, there is the difficulty in transmitting and receiving data between them due to difference in the program languages or the like. In this case, an adjustment for enabling or smoothing the data transmission required in their operations through their interfaces is definitely necessary.
To this end, in the case that a manufacturer of the tray changer is different from a manufacturer of the robot, a meeting between two manufacturers for such adjustment is required.
Even if the manufacturers have matched the tray changer with the robot in their specifications beforehand prior to the delivery of the system to a user, a similar meeting between them will be necessary again at a later timing if the specifications are changed due to addition or modification. This kind of inconvenience worsens the work efficiency. The necessary work will be doubled.